production of radioactive molecular beams
DESCRIPTION
Production of radioactive molecular beams. Christoph Seiffert CERN-ISOLDE \TU Darmstadt Supported by the Wolfgang Gentner programme. CERN/ISOLDE. https://mediastream.cern.ch/MediaArchive/Photo/Public/2008/0812015/0812015/0812015-A4-at-144-dpi.jpg. The Nuclear Chart. - PowerPoint PPT PresentationTRANSCRIPT
Production of radioactive molecular beams
Christoph Seiffert
CERN-ISOLDE \TU DarmstadtSupported by the Wolfgang Gentner programme
2
CERN/ISOLDE
https://mediastream.cern.ch/MediaArchive/Photo/Public/2008/0812015/0812015/0812015-A4-at-144-dpi.jpg
The Nuclear Chart
P
N
Isoltrap: 233Fr, 229Rn - new isotopes (K. Blaum et al.)
Windmill: Asymmetric b-delayed fission of 180Tl(A. N. Andreyev et al.)
First b-NMR experiment on soft matter(M. Stachura et al.)
Witch: Fundamental Symmetries
b-decay of 35Ar(M. Breitenfeld et al.)
Collaps: Size and Shape of Exotic Nuclei
Halo nucleus 11BeW. Nörtershäuser et al.
Biophysics
Precision measurement of 82Zn mass(S. Kreim et al.)
The Nuclear Chart
P
N
• Strong physics interest• 8-Boron:
• Neutrino source, β-beams• Halo nuclei• Boron as semi conductor
dopant • 9-Carbon:
• Investigations on 10-N• Decay structure
The Nuclear Chart
P
N
• Short lived isotopes of some light nuclei not available
• Reasons: • High boiling points • High adsorption enthalpy• Chemical reactivity
• 9-C seen once for 24h. Why?
Isotope Half life Boiling point [C]
8-B 770ms 3927
9-C, 17-C 123ms/175ms 3642
The Nuclear Chart
P
N
• Short lived isotopes of some light nuclei not available
• Reasons: • High boiling points • High adsorption enthalpy• Chemical reactivity
Isotope Half life Boiling point [C]
8-B 770ms 3927
9-C, 17-C 123ms/175ms 3642
Extract isotopes as molecular ions: CO+, BF2+
7
Production of Radioisotopes
1.4 GeV proton
fragmentation
fission
spalla
tion
238U
142Cs
11Li
201Fr
X
Y
8
Selection Process
HRS
GPS
beam lines
FE 6
FE 7
9
Steps In Isotope Extraction
Ionization
Isotope production
Effusion: interaction with target and line
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
Diffusion
Molecule formation
10
Isotope Production
Ionization
Isotope production
Molecule formation
Effusion: interaction with target and line
Protons
• 1.4 GeV proton beam from Booster• Depending on target material isotope production with cross section σ
Diffusion
11
Isotope Production
Computed with ABRABLA
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
I0=np*σ*δA
12
Steps In Isotope Extraction
Ionization
Isotope production
Effusion: interaction with target and line
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
Diffusion
Molecule formation
13
Diffusion
Arrhenius equation D0: maximum diffusion coefficient [cm2/s]
Ea: activation energy
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
14
Studies on BoronDiffusion studies with boron neutron depth profiling method (bndp) [10-B(n,α)7-Li ] Step 1: Implantation of 10-B as 10-BF2 into target materials
12.5 keV 10-B in Carbon
B
F
+
F
BF
+
F
15
Studies on BoronDiffusion studies with boron neutron depth profiling method (bndp) [10-B(n,α)7-Li ] Step 1: Implantation of 10-B as 10-BF2 into target materials Step 2: Measurement of (initial) distribution
σ[10-B(n,α)7-Li ]=3840 barn Pu-Be source: 1.1*10^8 neutrons/second @4Pi Same effect used in cancer therapy
α detector
16
Studies on BoronDiffusion studies with boron neutron depth profiling method (bndp) [10-B(n,α)7-Li ] Step 1: Implantation of 10-B as 10-BF2 into target materials Step 2: Measurement of (initial) distribution
σ[10-B(n,α)7-Li ]=3840 barn Pu-Be source: 1.1*10^8 neutrons/second @4Pi
Step3: Heating of Sample
17
Studies on BoronDiffusion studies with boron neutron depth profiling method (bndp) [10-B(n,α)7-Li ] Step 1: Implantation of 10-B as 10-BF2 into target materials Step 2: Measurement of (initial) distribution
σ[10-B(n,α)7-Li ]=3840 barn Pu-Be source: 1.1*10^8 neutrons/second @4Pi
Step3: Heating of Sample Step4: Repeat step 2 and step 3
18
Studies on BoronStudy on chemical behaviour and diffusion properties Boron can be extracted as a fluorideDiffusion studies with boron neutron depth profiling method (bndp) [10-B(n,α)7-Li ] Step 1: Implantation of 10-B as 10-BF2 into target materials Step 2: Measurement of (initial) distribution
σ[10-B(n,α)7-Li ]=3840 barn Pu-Be source: 1.1*10^8 neutrons/second @4Pi
Step3: Heating of Sample Step4: Repeat step 2 and step 3
Goal: Choice of target material which allows fast diffusion and therefore efficient extraction
19
Studies on Boron
α (1.418MeV)
Overnight measurement (Oct-2013)
20
Chemical Interactions
Ionization
Isotope production
Molecule formation
Effusion: interaction with target and line
Diffusion
21
Chemical interactions
Materials found in an ISOLDE target:
Tantalum
Molybdenum Copper
Rhenium
I=I0 *exp(-λ*(tdiff+teff)) *ε(chemical loss)*ε(ion source) *ε(formation)
22
Chemical interactionsChemical equilibrium of Ta and CO
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
Chemical equilibrium of Al2O3 and CO
23
Chemical interactionsChemical equilibrium of Ta and CO
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
Chemical equilibrium of Al2O3 and CO
Substitute materials which react with Carbon and Boron
24
Adsorption on surfaces
Sticking time:
http://www.buetzer.info/fileadmin/pb/HTML-Files/WebHelp/Die_Adsorption_von_Gasen_und_gel_sten_Stoffen.htm
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
25
Effusion
(1)Production of exotic, short lived carbon isotopes in ISOL-type facilities, Hana Franberg, Uni Bern 2008(2)Chemisorption on Rhenium: N 2 and CO JOHN T. YATES, JR., AND THEODORE E. MADEY National Bureau oj Standards, Washington, D. C. 20234(3)TPD measurements, Roman Bulanek, University of Pardubice, CZ(4) (Im)possible Isol beams, U.Koester et al, Eur.Phys.J.Special Topics 150, 285-291 (2007)
• Adsorption enthalpies for CO and CO2:
Adsorbent CO [kJ/mole]
CO2 [kJ/mole]
MgO -131 (1) -164(1)
HfO -66(1) -133(1)
SiO2 -22(1)
Al2O3 -35 (3) -65(1)/ -35 (3)
Y2O3 -16 (3) -80 (3)
Cu -96
Mo -126.4
Re -145(2)/ NA NA
Ta -962(4)/NA NA
• For > - 40 kJ/mole Chemisorption: strong interaction, irreversible, monolayer• For < - 40kJ/mole Physisorption : weak interaction (VDW Force), reversible, multilayer
Sticking time:
26
Chemical interactionsI=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
teff= Σ i= Σ ni*
Location ni
Target walls ~10^2
Grain walls >10^6
Location max [kJ/mole]
Target walls ~270
Grain walls 150
tmax=t1/2 =123ms9C
27
Chemical interactions
http://www.buetzer.info/fileadmin/pb/HTML-Files/WebHelp/Die_Adsorption_von_Gasen_und_gel_sten_Stoffen.htm
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
teff= Σ i= Σ ni*
Location ni
Target walls ~10^2
Grain walls >10^6
Location max [kJ/mole]
Target walls ~270
Grain walls 150
tmax=t1/2 =123ms9C
Structural material Target material
Tantalum Al2O3
Molybdenum HfO2
Rhenium Y2O3
Copper MgO
SiO2 CaO
28
Release Studies on CO+
Release studies at Off-line mass separator Injection of bursts of gas of interest (13-CO2, 13-CO, noble gases) Release gives information about release efficiency and time structure Investigation of different ion sources and materials
29
Release Studies on CO+
Release studies at Off-line mass separator Injection of bursts of gas of interest (13-CO2, 13-CO, noble gases) Release gives information about release efficiency and time structure Investigation of different ion sources and materials
30
Steps In Beam Production
Ionization
Isotope production
Effusion: interaction with target and line
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
Diffusion
Molecule formation
HELICON Ion SourceAn ion source for molecular beams
No hot tantalum surface Helicon developed by Pekka Suominen & Matthias Kronberger
[1]Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source , M.Kronberger et al, NIM B
Gas HELICON VADIS
CO 2.5 % -
CO2 0.3% 0.3%
I=I0 *exp(-λ*(tdiff+teff))*ε(ion source) *ε(formation)* ε(chemical loss)
HELICON ion source VADIS ion source
Ionization efficiencies
32
Thank you!
Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF)